Virginia has approximately one million acres of wetlands. An estimated 75 percent of these acres are palustrine vegetated wetlands, and the remaining 25 percent are estuarine wetlands. Virginia is believed to have lost about 40 percent of its original complement of pre-colonial wetlands.
A study of wetland trends in Southeastern Virginia for 1994-2000 showed a net loss of 2,100 acres (1.3 percent). The actual loss of vegetated wetlands was even higher, but offset by a gain in pond and open water area. The loss of palustrine wetlands was primarily due to conversion to uplands, while estuarine wetlands were lost through conversion to open water. Major causes of wetland loss in Virginia include conversion to other land cover types, ecosystem service modifications associated with climate change, hydrologic alterations, invasive species, fragmentation by development, crop fields, roads, fences, berms, and eliminated ecosystem services, notably habitat and water quality.
The Virginia Department of Environmental Quality (DEQ) and the Virginia Institute for Marine Science have developed a robust, science-based Wetland Monitoring and Assessment Strategy for evaluating the condition of wetlands in the Commonwealth. The overarching goal of Virginia’s strategy is to devise a long-term implementation plan for a wetland monitoring and assessment program that protects the physical, chemical, and biological integrity of the Commonwealth’s water resources, including wetlands. In order to accomplish this goal, it is critical to first know the status of wetland resources in Virginia, in terms of location and extent of wetlands in each watershed, and have a general knowledge of the quality of these wetland resources. Second, the functions of wetland resources impacted through the permitting program must be accurately evaluated to determine those functions to be replaced through compensatory mitigation. It is also important to assess the degree to which the required compensatory mitigation is performing in relation to those impacted functions.
The assessment method is a multi-service model that involves three levels of data collection. The method characterizes the capacity of the wetland to provide water quality and habitat services using remotely sensed data. The model application produces a relative score for each wetland for each service. The scores are then refined and calibrated by site visits to randomly selected wetlands. The relationship between structure and function is validated by intensive study of ecological service endpoints.
Results to Date:
The data collected from the assessment has been compiled into an online GIS-based wetland data viewer identified as the Wetland Condition Assessment Tool (WetCAT). WetCAT can be used to evaluate wetland condition over time, make better permitting decisions relative to cumulative impacts, avoid and minimize wetland loss, evaluate performance of compensatory wetland mitigation in replacing wetland acreage and function, and evaluate the effectiveness of the regulatory program.
Virginia’s wetland monitoring and assessment program is being implemented by funds awarded through U.S. EPA’s Wetland Program Development Grants to continue these efforts. DEQ has received nine grant awards from EPA for this initiative, and Virginia is recognized as one of five states leading this initiative nationally.